Quantitative evaluation after arthroscopic anterior cruciate ligament reconstruction. Allograft versus autograft

We measured the anteroposterior ligamentous laxity and thigh muscle power in 92 subjects who were rated as successes after they had undergone arthroscopic anterior cruciate ligament reconstruction for unilateral anterior cruciate ligament insufficiency 18 to 36 months previously. The subjects were divided into 2 groups according to the type of graft: fresh-frozen allogenic tendon (N = 47) or central one third of the ipsilateral patellar tendon (N = 45). Instrumented drawer tests in the Lachman position were performed to measure anterior tibial displacement at 200 N (anterior laxity). Thigh muscle power was isokinetically measured with a Cybex II dynamometer. Significantly more anterior laxity was found in the reconstructed knees than in the contralateral normal knees regardless of graft material (paired t-test, P < 0.01), except for the male allograft patients. Although the mean anterior laxity difference between sides for the allograft patients was less than that for the autogenous ones, analysis of variance failed to demonstrate a statistically significant difference between the 2 groups if the comparison was strictly made within the same sex. Thigh muscle tests revealed that extension torque in the reconstructed knees was significantly less than that in the contralateral knees and analysis of variance showed that knee extension torque at 60 deg/sec for the allograft patients was significantly better than that of the autograft ones (P < 0.05). We concluded that the allograft procedure is advantageous over the patellar tendon autograft in terms of better restoration of anterior stability.